Canadian Horseweed, Fleabane, Hogweed

Conyza canadensis

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Conyza (kon-NY-zuh) (Info)
Species: canadensis (ka-na-DEN-sis) (Info)
Synonym:Erigeron canadensis
Synonym:Leptilon canadense




Foliage Color:

Unknown - Tell us

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Water Requirements:

Drought-tolerant; suitable for xeriscaping

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Unknown - Tell us


12-18 in. (30-45 cm)

18-24 in. (45-60 cm)

24-36 in. (60-90 cm)

36-48 in. (90-120 cm)

4-6 ft. (1.2-1.8 m)


24-36 in. (60-90 cm)


Not Applicable

Sun Exposure:

Full Sun


Handling plant may cause skin irritation or allergic reaction

Bloom Color:

White/Near White

Bloom Time:

Mid Summer

Late Summer/Early Fall

Mid Fall



Other details:

May be a noxious weed or invasive

Soil pH requirements:

Unknown - Tell us

Patent Information:

Unknown - Tell us

Propagation Methods:

From seed; direct sow after last frost

Self-sows freely; deadhead if you do not want volunteer seedlings next season

Seed Collecting:

Bag seedheads to capture ripening seed

Allow seedheads to dry on plants; remove and collect seeds

Properly cleaned, seed can be successfully stored


This plant has been said to grow in the following regions:

Phoenix, Arizona

Morrilton, Arkansas

Chula Vista, California

Sebring, Florida

Anna, Illinois

Itasca, Illinois

Benton, Kentucky

Brookeville, Maryland

Pinconning, Michigan

Pawling, New York

Battleboro, North Carolina

Terrebonne, Oregon

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Gardeners' Notes:


On Mar 18, 2015, lincoln8 from Gerald, MO wrote:

just found out this is useful in ulcerative colitis/ referenced in Michael moore and Micheal Alfs


On Jul 1, 2009, tcs1366 from Leesburg, FL (Zone 9b) wrote:

I pull this plant out by the bushel full every year... it just keeps coming back. Only good thing is, it's easy to pull out, even in my rock hard soil.


On Jan 3, 2005, melody from Benton, KY (Zone 7a) wrote:

This weed has an amazing ability to flourish and set seed in just about any conditions.

It ranges from nearly 10 feet tall in loamy bottom land to just a few inches high on rocky abandoned lots. In both cases, it sets vast amounts of seeds and is virtually indestructable.

It is invasive and as far as I know, livestock avoid it.


On Nov 2, 2004, xyris from Sebring, FL (Zone 9b) wrote:

Can we accept that some weeds have little to no garden value? I think this is one of them. I find it growing abundantly only in disturbed areas, and is one of those weeds that is impossible to keep out of a sandy soil garden (and probably other soil types).


On Oct 27, 2004, cityboy from ft. worth, TX (Zone 8a) wrote:

Grows well without human intervention. Best planted as a group.